Bobbin having a controlled unwinding



Jan. 31, 1956 R. N. ROBINSON 2,732,317

BOBBIN HAVING A CONTROLLED UNWINDING Filed Oct. 28, 1953 INVENTOR. 1Rowland N.Ro|:a1nson ATTORNE Y United States Patent C) BOBBIN HAVING ACONTROLLED UNWINDING Rowland N. Robinson, Worcester, Mass., assignor toThe Robinson Thread Company, Worcester, Mass a corporation ofMassachusetts Application October 28, 1953, Serial No. 388,807

Claims. (Cl. 112-251) This invention relates to a bobbin of wound layersof thread made of artificial fibres, and more particularly to a bobbinfilled with such thread which is primarily adapted for use in a highspeed sewing machine.

The standard natural fibre thread, such as cotton, has crinkled fibresprojecting laterally which so interlock that juxtaposed threadconvolutions wound on a bobbin cling together somewhat and thus presenta slight degree of friction or resistance to unwinding which tends tohold the thread in place and insure an orderly feeding of the threadfrom the bobbin in a sewing machine shuttle. On the other hand, moderntypes of thread made of artificial or synthetic polymeric fibers, suchas anylonpolyamide .substance, are cylindrical filaments which offer butlittle adhesion at the surface to adjacent :thread portions.Consequently, when a bobbin filled with such artificial thread isemployed in a high speed sewing machine shuttle and the machine isstopped abruptly, as is customary in industrial usage, the bobbincontinues to spin and the comparatively slippery or non-coheringconvolutions of the thread tend to unwind from the bobbin and be,caughtaround the bobbin post or otherwise entangled in the shuttle.Such spilling, unwinding or ibacklashing of the thread results inbreakage of the thread and interferes with the sewing operation.

It has been proposed toomit the core and end disks of an externaldelivery bobbin .and .to form a self-supporting cotton thread mass byimpregnating the wound thread with wax. This has proven impractical,especially because the shape ultimately becomes distorted so that thebobbin will not fit over a-shuttle post properly. Also, the forcerequired to turn the bobbin increases as the radius of the wound threadbody decreases, especially toward the end of the thread supply, and"this variation in the thread tension interferes with the setting of thestitch and proper concatenation of the "loops in the seam, so that themachine operator :commonly removes and throws away the bobbin while itstill contains considerable thread. It hasalso been proposed tomake thebobbin end disks of paper and to glue them directly'to the mass of woundcotton thread, but this has required the use of a strongly bondingadhesive which interferes with the thread unwinding'as rwellas leaves anabrasive powdery deposit in the shuttle. Attempts have been madesimilarly to use sheet gelatin for the :bobb'in ends, or to dip the endsof the thread :body i'nmolten wax and die press the coating into .theacquired bobbin end shape. Such gelatin or wax ends are supported solelyby the thread, so that as the thread unwinds the support decreasesindiameter and area until one or both of the end disks becomes separatedfrom the core and the thread then .catches around the shuttle post andbreaks. Such wax ends were also to be die imprinted with lines ofweakness, so that the 'wax which clings strongly to the cotton fibrescould break away in fragments and the ends would .disappearas the threadunwound, but this required that the thread carry adhering pieces of waxwhich could interfere with the sewing operation. In order to heatinsulate a central delivery bobbin of waxed thread used for sewingleather and thus to prevent collapse of the thread mass, it has beenproposed to coat the outer surfaces of the bobbin with sodium silicateor to cement disks of fibrous material on the bobbin ends. Suchprocedures are not applicable to an external or peripheral deliverybobbin of artificial fibre thread. 7

In my experimentation, I have found that an artificial or man-made fibrethread, such as nylon, should be held in position on the bobbin coreunder a controlled restraint so that it may unwind substantially freelyand yet cannot unwind or spill materially, such as when the bobbin isdropped onto the floor or overspins in the shuttle.

The primary object of my invention is to provide an external deliverybobbin of layer wound artificial or synthetic polymeric fibre "threadwhich will unwind under a controlled restraint but substantially freelyin the shuttle and not interfere with the sewing machine operation,whereby the thread is held in place and delivered under a suitable butlight tension which insures a uniform setting of the stitch formationand resists the tendency for the shuttle to continue to spin when themachine is stopped,

H so that the thread cannot unwind accidentally into a loose and tangledmass but is held substantially in place on the bobbin core by anadhesive force which may also serve for rewinding on the spinning bobbinany thread that has become loose in the machine. Further objects will beapparent in .the following disclosure.

in accordance with this invention, I employ a synthetic or artificialfibre thread, asherei-n defined, and I wind this thread on a bobbin corein a helical'winding and preferably in a criss-crosslayered arrangementso that the thread will travel rapidly from one side to the other as thethread is unwound. .A standard filled "bobbin weighs 3 to 4 grams. Thethread convol-utions thereof are tacked to adjacent or contiguous threadportions or convolutions to provide a'slight resistance to an accidentalunwinding by means of an adhesive cement capable of adhering to thesynthetic fibre substance and of being entrapped in the threadintermeshes and =aifixing the thread convolutions with a slightdegree-ofadhesion which holds the thread in place during disusej but :withoutproviding a sticky, gummy or powdery mass as the thread is unwound.Although there is wide latitude as to the area of adhesion, it ispreferably established at spaced intervals and for only .a slight lineardistance along the thread. For a cross wound thread, the adhesions arepreferably at the ends of the thread mass and are usually spacedlinearly of the thread by a :distance of not more than about thecircumference of the'th'read wound layer, such "as one or two pointsiforeach layer, as shown in Fig. 1, although the spacing may be widelyvaried for the diiferent types of :thread. The thread winding may haveadhesive arranged between spaced convolu'tions in a line or band, asshown in Fig. 5, or I *may'employ a plurality of such radial .adhesionsspaced parallel with the bobbin axis or a continuous band of slightlyadhering cement throughout the entire bo'b'bin length. These adhesionsprovide a slight resistance to the unwinding pull and yet permit asubstantially free unwinding under the normal thread tension ofa-sew'ing operation. The force required to free the thread end {from thebobbin s'holild be sufiicient to insure that the thread is tacked to thethread body and preferably with enough but not greater strength than isneeded barely carry the weight of the bobbin when suspended from thatthreadend The adhesive substance is selected from "a group of substancescapable of adhering-to .the synthetic fibre, and it 'is preferably aplasticized thermoplastic polymerized resin body or a solution'thereof,which causes adhesion of adjacent thread layers or convolutions and yetbecomes such a part of the thread substance that when the threadadhesion is pulled apart there is no scattering of adhesive or powderymaterial which can in any way interfere with the sewing operation.

Referring to the drawings:

Fig. 1 is a digrammatic view, partly broken away, of a bobbin carrying across-wound thread having a cement applied to the sides of the threadbody;

Fig. 2 is a diagrammatic view of a few juxtaposed cross-wound threadportions showing their relation to the adherent side coating of cement;

Fig. 3 is a fragmentary end view of a few convolutions of thread on thebobbin; v

Fig. 4 is a diagrammatic fragmentary view of mechanism for applying theadhesive to the sides of the thread mass; and

Fig 5 is a diagrammatic view of a thread mass wound on a bobbin andhaving a narrow line of cement applied to its convolutions, and showingan applicator for the cement. Y

The spaced adhesions are preferably provided by applying a suitableadhesive to a side and preferably both sides of the cross-wound bobbinthread mass, which insures an adhesion of contiguous loops of thecrosswound thread at the edge of the bobbin where the thread changes itsdirection of travel, as is indicated in Figs. 2 and 3. It is alsofeasible to apply the adhesive progressively to the periphery of thethread mass during the winding step, as shown in Fig. 5, such as bymeans of an adhesive feeding disk rolling against the periphery of thewinding thread which deposits a narrow band of adhesive on the top ofthe mostrecently wound thread layer, so that as the next layer is laidthereover the two will'stick together at this narrow band. Several bandsof adhesive or a single wide band of any desired width may be used onthe various types of thread winding.

Referring first to Figs. 1 to 3 inclusive, a bobbin usually comprises ahollow cylindrical core 10, which may be made of paper, plastic, metalor other suitable material, and disc-shaped ends 11 of the same or othermaterial suitably secured to the core, as by flaring the outerprojecting ends of the core laterally (Fig. 1) to form flanges lappingover the outer faces of the disks. The thread is wound on the corebefore the disks 11 are applied, in accordance with standard practice,to provide a crisscross winding of the thread 12, wherein the thread isfed to the rotating bobbin by means of a reciprocating arm. If thiswinding is what is commonly termed a one-wind, the thread travels fromone side face to the other during a single revolution of the bobbin. Ifthe thread travels from one side of the bobbin to the other in half abobbin revolution, this isa half-wind. A-twothirds wind is shown inFig.1. I prefer that the winding thread make at least one transversepassage. during about one revolution of the bobbin. That thread 12 willcome up to the lateral face of the bobbin, and then change its angulardirection of travel at the loop or bend 13. In the next revolution ofthe bobbin, the thread will overlie the thread close to the previouslyformed loop 13, as indicated in Fig. 2, so that the side of the woundmass will present a series of these loops. .The rate of reciprocationrelative to the rotation of the bobbin is preferably so governed thatthese loops or change of direction of the thread do not ,lie on top ofone another but are disposed in an orderly fashion in concentric circlesat the end of the wound thread, as shown in Fig. 3, or in otherarrangement dependingon the winding operation.

In accordance with one phase of my invention, I afiix the adhesive14 tothese loops 13 where they project at the side face of the bobbin andbefore the bobbin ends 11 are affixed to the core. That is, the. threadis wound on the cylindrical hollow core and then the adhesive isapplied, and after the adhesive has set and depth of penetration by theadhesive.

accomplished its purpose the bobbin ends 11 are suitably fixed in placeto form sides close to but unattached to the thread mass so that thethread will not slip off the ends of the wound mass and become entangledaround the core.

The application of the plastic resin may be accomplished either manuallyor mechanically. Manual application of the adhesive may comprisespraying the ends of the bobbin or dipping the same in a shallow bath ofthe cement or a direct application by means of a paint brush or apressure contact with a porous surface filled with a plastic resin or asolution thereof. If the application is done mechanically so as toprovide a better control of the amount of adhesive, the wound bobbinmass may be suitably mounted on a spindle 15, as shown in Fig. 4, andtwo reciprocable carriers 16 are brought up against the side faces ofthe wound bobbin to apply the fluid adhesive thereto. Each carriersuitably supports a porous disk 18 of felt or other porous materialwhich is arranged to be pressed against the side faces of the thread. Aset of ducts 19 running through the carrier serves to feed the fluidadhesive to the rear of the disk 18 from an outside source and thuspresent a film of adhesive for application to the thread. 'Variousexpedients may be adopted to provide a satisfactory distribution of theadhesive. When each of these carriers 16 with its adhesive loaded disk18 is brought into contact with the sides of the bobbin, this serves toleave a deposit of the plastic on the projecting loops 13, as shown inFigs. 1 and 2. The pressure of the plates 18 on the thread mass may beadjusted to insure an adequate Thereafter, the carriers 16 are withdrawnand the bobbin is ready for further treatment, such as for applying thedisk ends 11 to the core.

It is desirable to control'the amount of adhesive applied, so as toprovide a definite adhesion strength. The amount applied by themechanism shown in Fig. 4 will depend to some extend on the pressure ofthe porous disks 18 against the bobbin sides as well asthe amount ofplastic that is impregnated into the disks. Ordinarily, the amount is tobe such that the plastic resin will not penetrate the intersticesbetween the thread fibres or filaments for more than about three timesthe thickness of the thread and preferably a lesser distance. Theprimary requirement is that the thread will remain attached at the loop13 to an adjacent loop or thread portion so that a free end of thethread will not ordinarily loosen from the bobbin beyond that point. Itis preferable that the outside end 20 (Fig. 1) of the thread be tackedto the body at loop 13 with sufiicient adherence so that the adhesion atthe loop will be just about enough to support the weight of the bobbinwhen suspended from the thread end. The cement is present primarily inthe interstices between the threads or their multiple filaments, andthere is primarily a physical interlocking of the adhesive with thesefilaments which holds the parts in place. Although the plastic may be ofa type which dissolves the filament substance to some extent and somakes an intimate union therewith, I preferably use a non-solvent sothat the bonding efiect is primarily due to its mechanical interlockingwith the filaments throughout the short distance represented by thelength of the loop 13, as well as by direct adhesion.

As the thread unwinds from the bobbin, the intervals between the afiixedloops 13 become shorter, since there are the same number of loops perrevolution of the bobbin and these are therefore spaced more closely asthe bobbin center is approached. Hence, an adhesive condition which issatisfactory for the outer convolutions of thread may provide too muchadhesive at the innermost.

convolutions, and particularly since the force required to remove thethread from the bobbin increases as the bobbin diameter decreases.Hence, as a further feature of this invention, I may omit the plasticcementitious contacts or adhesions at that part of the bobbin which isnearest to the core, and preferably at least throughout the first fifthof the wound diameter of the bobbin. This is especially applicable tothe large bobbins where the .periphery is at least 3 or 4 times the corecircumference. This provision is not required for the smaller bobbins,where the entire side may be coated. To this end, I may provide a flangeor ring 21 (Fig. 4) mounted on each carrier 16 concentricallysurrounding the arbor on which the bobbin is mounted. This ring 21 actsas a guard to prevent the adhesive from touching the side of the bobbinnear the core 10. The ring may be suitably mounted in a recess 22 withinthe carrier 16 and held forward by a helical spring 23 under compressionwhich applies sufiicient force to hold the collar 21 against the side ofthe bobbin during the application of the ad hesive therearound. Hence,as indicated in Fig. 1, the adhesive may terminate at the circular line24 and leave the innermost portion of the unwinding threadfree withoutany adhesive to restrain its movement. If this ring is omitted, then ofcourse theadhesive will be applied largely throughout the entire sideface of the wound mass.

According to another aspect of my invention, a line of adhesive may beapplied to the periphery of the thread mass during the windingoperation. This may be accomplished, as indicated in Fig. 5, by suitablemechanism comprising a metal applicator disk mounted on the shaft 31 anddipping at its lower end in a bath 32 of fluid adhesive. The shaft 31 ofthe disc 30 is so mounted, preferably under spring action, that the diskremains in frictional driving contact with the gradually growingperiphery of the bobbin mass 34 as it is being wound. If the adhesive isnot to be applied to the inner convolutions, then, as illustrated in thedrawing, the wheel 39 may be brought into contact with the winding massafter the desired diameter, suchas 9% of the total diameter of the woundmass, has been attained. The disk 30 may be narrow and leave only a veryslight amount of adhesive 35 on the outer-portion of each convolution orlayer of the Wound thread, and the spring which holds the disk 30against the bobbin should introduce only a controlled and slightamountof the plastic cement to the thread. threads are formed by theplastic deposited on the top of one layer of the thread mass whichadheres to the next layer of thread that is applied thereover. The .net

result is the same, in that spaced adhesions are provided for desireddistances or at spaced intervals. Thedisk 30 may be of suitable width,or several disks 30 may be used in parallel to provide continuous orspaced bands.

The standard'artificial fibre substances capable of use as threadscomprise the standard synthetic polymeric.

resins, and particularly the linear polyamide resins, acrylic resins,polyester resins, vinyl resins, amyl resins, and copolymers thereof; andthey include the cellulose base substances, such as cellulose acetaterayon, ethyl cellulose viscose rayon, cuprammonium nitrocellulose rayon,

, the protein base substances made of regenerated silk,

soy bean, zein, fish and Waste animal tissues, spun glass, andartificial fibre substances derived from natural fibres,

, such as regenerated silk or viscose made by extruding dissolved cottonlinters. One example is the thermoplastic nylon condensation product ofadipic acid and hexamethylene diaminc. Another such'standard thread ismade of an Orion acrylonitrile. A Dacron poly-- ester thread fibre maybe made from a condensate of ethylene glycol and terephthalic acid. Allof these synthetic or artificial thread fibre substances are includedunder the general term of artificial fibre thread, and the filaments ofwhich the threads are made are herein classed as-fibres. I

A suitable adhesive substance for tacking together spaced portions ofthe artificial fibre threads may be se lected from the group ofpolyamide, acrylic and polyester in this case, the adhesions between thed resins and the natural and synthetic rubbers suitably plasticized byplasticizers or solvents, and especially polyvinyl acetate, polyvinylalcohol, vinyl chloride, polystyrene, nylon" polyamide type 8,polyacrylonitrile, melamine formaldehyde, the methacrylates, thecumarone resins, the furan resins and copolymers thereof, the naturaland synthetic latices or solutions of rubber and the synthetic rubbers,such as the polychloroprene, polybu'ta'diene, 'polysulfide andpolybutene rubbers, and various copolymers and related substances whichhave an affinity for and are able to adhere to and cause cohesion ofadjacent synthetic or artificial thread fibres. Such substances, hereinclassed as poly meric resins, may be plasticized vwith various types ofplasticizers or solvents which are commercially avail able, and theseare employed in quantity and composition to give the desired viscosity,adhesion and other needed physical properties. It is preferred to use aplasticized resin adhesive which is not only compatible With and adheresto the artificialt'hre'ad fibre, but is insoluble in mineral oil oftenfound objectionably present near sewing operations.

As an example of a suitable composition of general utility for thevarious artificial fibre threads, a polyvinyl acetate adhesive may becompounded of:

12.5 lbs. polyvinyl acetate 1.0 lb. dibutyl phthalate 0.75 lb. water itsp. aqueous ammonia, 28% strength After application to one or bothsides of the bobbin.-

wound thread, the thread may be suitably heat treated to insurehardening of the adhesive. This may be effected by curing the threadmass in an oven having air circulated at 250 F. for 15 minutes.

A nylon thread may be provided with suitable tackiness or adhesivenessby an adhesive made according to the following formula:

1 lb. nylon polyamide type 8 2 lbs. water 8 lbs. ethyl alcohol 2 oz.ethyl hexanediol This substance after application to the thread may bedried at room temperaturefor24 hrs. in order to cure the resinsubstance.

Another satisfactory adhesive may be formed of: 5 lbs. polyvinyl butyral(containing 50% of solids) 5 lbs. water 2 lbs. melamine It will now beappreciated that the thread tacking sub- Z stance shouldhave an alfinityfor the synthetic or artificial thread fibres to the extent of adheringto and interlocking adequately-therewith, without flaking off as abrittle or abrasive powder. I have found that mucilage and many othersubstances which would adhere to cotton or woolen are not adequate forthe purpose of tacking together the adjacent thread loops orconvolutions of synthetic polymeric thread fibres, and particularlysince they do not have the required tensile film strength. The.synthetic fibres do not absorb the adhesive fluid the way cotton andwool do, since the adhesion is principally due to an interlocking withthe many filament strands of the synthetic thread, as well as a directsurface film adhesion. The synthetic;

polyvinyl butyral, polyfibres are hydrophilic, and I do not use a watersolution of adhesive, except as water may be used as an evaporablecarrier of the resin. Itis desirable that the thread con volutions betacked together only lightly and with a substance which eitherdisappears into the thread body or is otherwise of such' a nature as notto become separated from the thread to a detrimental extent.

The synthetic resin applied to cause cohesion of the thread convolutionsis preferably applied in such a minute amount that it does not penetratethe thread body more than ordinarily three times the thickness of asingle thread and the resin film should not ordinarily exceed 0.002 inchin thickness as a layer on the ends of the thread mass. The adhesion isprimarilybetween very short lengths of thread where they are in contactwith the neighboring thread convolution at the bobbin edge, as indicatedin Fig. 2 or in a line contact, as shown in Fig. 5. For example, if thethread wound on a bobbin measures 0.005" in thickness, the resin filmwill ordinarily be satisfactory if itpenetrates only about 0.015" intothe side of the thread mass, although this depth of penetration mayvary, depending upon the nature of the thread and the usage to which itis to be put. The amount of substance em ployed is gauged to'some extentby the forces required to free the thread from the bobbin withoutinvolving a jerky motion as the thread is pulled forward. This force maybe 3 to 4 grams. This involves a ratio of 0.2% to 2.0% of the tensiiestrength of a nylon thread, for example. It is to be observed thatthreads with low tensile strengths, such as 1 lb., or with highstrengths, such as 25 lbs., and with diameters varying from 0.002" to0.025" require little difference in force to free them from the plasticcoating. In each instance, the strength is merely sufficient to hold thethread mass tacked together and provide a substantially free butslightly restrained unwinding thereof and preferably to insure a backwinding of any loose mass of the thread if the bobbin should spin afterthe machine has been stopped; The quantity of adhesive applied iscontrolled in part by the pressure and the duration of time ofengagement of the disks 18 against the thread, as well as the quantityof fluid adhesive introduced through the ducts 19 to the disk 18. a

It is desirable to maintain the plastic mass as mobile as possible inorder to obtain a uniform application to the thread on the bobbin.Ordinarily an absolute viscosity of less than 200 poises is advisable,and I prefer that this be within the range of 10 to 75 poises. Theviscosity depends on the nature and quantity of plasticizer or solventused. The penetration into the thread mass may be controlled in variousways, such as by limiting the amount applied to that which insures theproper penetration. It is desirable to limit the plasticity of theplastic resin film on the thread to a range of 10 to 50 Shore DurometerType A hardness. In order to guard against brittleness and a consequentscraping of the material from the thread, it is preferable that theadhesive have a slight tackiness and not be brittle or in danger ofsloughing off as a residual deposit in the shuttle case. The resin maybe always soft, as is the case with polyethylene glycol plasticizedresins.

The thread convolutions are tacked together at intervals of preferablynot greater than about the circumference of a cross wound thread layerand throughout only a very short distance and particularly at spacedintervals where one adhesive coated thread convolution touches another.If the thread is a one-wind, or wherein the thread travels from one sideface of the bobbin to the other during a single revolution thereof, thenthe tacking of one thread convolution to another will take place only atthe loop where the thread changes in its direction of travel, and atypical bobbin measuring 0.75" to 1.0" in thickness will have eachthread convolution aflixed to the adjacent thread mass at points ofabout & in length and at intervals spaced at about 2%". If the threadwinding is a half windyor where the thread makes two passes across thebobbin in a single revolution of the bobbin, the

thread will make a sharper angle where it changes its direction oftravel and the length of the afiixed loop portions of the thread will beslightly less than 5 and the intervals between the afiixed points willbe about 1%".

If the thread is wound helically where many revolutions of the bobbinare required for the thread to travel from one end of the bobbin to theother, I may use a gang of parallel applicator disks'30 which providespaced disklike adhesions within the thread mass, so that the linearlyspaced adhesions are separated by a distance of only a small multiple ofthe thread layer circumference. These axially parallel adhesions preventany accidental unwinding of a long length of thread. Where the thread iscross wound, as in Fig. 1, the adhesions are properly localized by beingimpregnated only into the loops 13, and the length of thread between theadhesions is determined by the nature of the cross winding, such as thelength of the circumference of each thread convolution layer for aonewind. The adhesions in the winding of Fig. 5 are formed by the narrowband 35 on each thread layer which forms an internal disk of adhesionsperpendicular to the axis of the thread body and located suitablyanywhere between the bobbin ends, so that each thread layer is tacked tothe two layers located radially of the bobbin on each side thereof.

It will be appreciated that various'rnodifications may be made in thebobbin winding and the manner of tacking the thread convolutionstogether and that I may employ various adhesives which are capable ofadhering to the artificial fibre thread substances and forming adhesionsbetween the convolutions which satisfy the above objects of myinvention, and that the viscosity, quantity, adhesivenessand nature ofthe cement may be varied as needed according to the type of threadsubstance employed. Also,

' the extent of area or volume of impregnation may be varied widely,provided the resin cement is impregnated into v the body throughout therequired portion in such a limited quantity that the thread is tackedtogether sufficiently to prevent an accidental unwinding but notsufiicient to bind the mass into a self-supporting unit which does notrequire the thread confining ends. In my bobbin, the thread is wound ona core and disk ends are required to confine the thread mass on the coreso that the cement in any portion of the thread mass is presentprimarily to prevent accidental unwinding and not to bind the mass intoa selfsupporting unit. Hence, the above disclosure of the principles ofmy invention and the description of preferred embodiments is not to beinterpreted as imposing limitations on the appended claims.

I claim:

1. A thread bobbin comprising a core, a mass of thread formed of smoothsurfaced artificial fibres cross wound thereon in helical convolutionsfor external delivery, the cross winding of the thread providingradially arranged loops at an end of the thread mass, an adhesiveapplied to the exposed loop surfaces and impregnating the loops at saidend of the mass for only a short distance, the main body of the threadbetween the ends of the wound mass being non-coated and free forunwinding, disk ends secured on the core which are independent of andsolely confine the thread mass on the core, said adhesive being acompatible heat set polymeric resin film independent of the disk endswhich tacks radially adjacent thread convolutions together and providesa substantially free unwinding ofthe thread and which requires a tensileforce of not over about four ounces to pull the thread free at thetacked loops.

2. A thread bobbin comprising a core, a mass of thread formed of smoothsurfaced artificial fibres cross wound thereon in helical convolutionsfor external delivery, disk ends secured on the core which areindependent of and confine the thread mass therebetween on the core,said core and disk ends formingthe sole support for the thread, and apolymeric resin adhesive independent of said disks and located in thethread interstices between adjacent convolutions which is compatiblewith, adheres directly to and tacks the thread in place at narrowadhesion points widely spaced linearly along the thread, the main bodyof the thread being non-cohesive and unwinding freely between saidpoints, the force of adhesion at said points being only sufficient torestrain the thread against accidental unwinding without providing aresistance to unwinding during a normal use which is materially greaterthan that of the adjacent untacked portion.

3. A thread bobbin according to claim 2 in which the thread loops aresubstantially free from said adhesive for a distance outwardly from thecore of at least about onefifth of the initial radial thickness of thewound thread mass.

4. A thread bobbin according to claim 2 in which the polymeric resinadhesive penetrates the thread interstices not over about three timesthe thickness of the thread, and the force required to break theadhesion is not substantially greater than the weight of the bobbinsuspended from the free thread end.

5. A thread bobbin according to claini 2 in which the I References Citedin the file of this patent UNITED STATES PATENTS 945,562 Cone Apr. 12,1910 1,135,470 Tolman Apr. 13, 1915 2,148,339 Cryan Feb. 21, 19392,200,720 Morin et a1. May 14, 1940 2,200,721 Marinsky et a1. May 14,1940 FOREIGN PATENTS 328,944 Great Britain May 5, 1930

